sub-storage stations, the inventor being Mr. King, of the E. P. S. Co. The main generating and storage station is at Draycott Place, Cadogan Terrace. The dynamos are built by the Anglo-American Brush Company. There is, as it were, a sub-station of accumulators in the same building. In the battery room there are 3 tiers of cells, in all 12 sets of 54 cells each. The cells are glass in wooden trays lined with sawdust. The boxes rest on glass insulators containing rosin oil. Each cell weighs 200 lbs., and is supported on wooden crosspieces fixed to iron uprights. The regular discharge is about 60 amperes for 9 hours. Two sets run 3000 30-watt lamps of 13 candlepower. Traveling cranes assist in changing cells. The mains are laid under the sidewalks at the curb. Several sub-stations are undergoing construction, one was in operation at the time of my visit. It is situated in a stable at Clayton Mews. Eight sets of 53 cells each are attached to 2000 30-watt lamps, and furnish a constant and satisfactory supply of current Ventilation is effected by a fan driven by a 1-3 horse-power motor, but is seldom necessary. The feeders are at times automatically joined to C. E. M. F. cells of plain lead grids.

In such a station the batteries are divided into two parts. When the engines start, one set is supplying current for day consumption, the other is thrown into circuit and is charged, then switched onto the mains, and the second set is switched on the dynamo circuit and charged, and when this is completed it is put in multiple with the first set and begins to discharge. This is accomplished before the heavy lighting begins. The cells are cut out of the charging circuit automatically, when charged, by a master cell from which the gas evolved raises a gas-holder and makes contacts that allow current to move switches. The regulating devices are exceedingly ingenious, and though somewhat complicated work well. A great future is before this system if, as seems likely, it stands the test of actual work for a long time. The E. P. S. Co. guarantees the cells to have less than 12 per cent depreciation.

House lighting in England is considered of the first importance in central station work, and the House to House" Electric Light Supply Company has done good work in several cities. Its station at Brompton is a model one. It is designed for 12 complete sets of plants of which 3 are now running. Babcock and Wilcox boilers are used, connected by copper tubes to the main steam pipe of welded

steel. Copper tube for the entire steam piping is common practice in England. The temporary partition of corrugated iron at the end will give room for nine more boilers in addition to the three now in use. The chimney is large enough for six. All exhaust piping laid under the floor is large enough for 12 boilers. The three engines are compound non-condensing of the Corliss type, and belted to the dynamos by seven separate ropes. They are steam jacketed, and with 140 pounds of steam develop 250 to 300 horse-power.

The Lowrie-Parker dynamos have revolving fields and stationary armature and make 350 revolutions, producing 60 amperes at 2000 volts. The exciters are driven from a small counter on the armature shaft. The details of this system are well worked out. The dynamos are often run in parallel, a feat not attempted elsewhere. To deter mine when two dynamos are in step a lamp is connected to two secon daries in series, the primaries being one in the circuit of each machine. When the phases of the two dynamos coincide the lamp burns brightly, and the switches are then thrown. The mains are under ground, of stranded wires insulated with india rubber.

All of the stations described thus far in London are removed from supplies of water for condensing purposes, and where coal of extra quality must be used to prevent smoke nuisance. To attain the high degree of economy in condensation, to avoid the expense of carting coal, etc., the London Electric Supply Company located a station at Deptford, five miles from the city, to which a current of 10,000 volt alternating will be carried in concentric cables running by the viaduct of the South Eastern Railroad and the Underground Railroad to substations at Charing Cross, etc., and there transformed to reduce the pressure from 10,000 to 2500 volts, which is distributed by underground mains in bitumen conduits to consumers, and again converted to currents of 100 or 50 volts. So gigantic an experiment as this was not entered upon by chance. A small station in the basement of Grosvenor gallery became a success a few years ago when Mr. Ferranti's system was adopted. Over 30,000 lights are run from this station. The mains are overhead on housetops. The E. M. F. employed is 2500 volts, so that the Deptford installation is not wholly experimental. The saving in the cost of coal is as 22 shillings to 8 shillings 9 peuce, or as from $6 to $5.50 to $2.18. The engines now operating are upright marine compound condensing Corliss, working

at 160 to 200 pounds pressure. Condensation is not yet provided for. The Thames water or sewage is very dirty, and it is necessary to go out 200 feet from the dock at low tide to find water, at which a mud beach extends 75 feet from the wharf, -a mud beach so soft that vessels are not injured by resting on it.

The compound engines and exciters would for a small town be a large plant. But the large dynamos recently started are 30,000 light machines, and these are small compared with the monsters in process of construction. They will weigh 600 tons. The armature will be 42 feet diameter and the frame 45 feet. The speed will be 50 to 60 revolutions. These engines being two of 10,000 horse-power to each machine directly connected. The crank shaft alone will weigh 26

tons.

The boilers of Babcock & Wilcox type, by means of forced draft obtained from blowers driven by engines under boiler room, are capable of generating 800 horse-power each. The gases from the furnaces pass at will through economizers to a 130-foot stack. When finished in two stories there will be 48 boilers. Railways connect every part of the works and yard. The engine room has two large overhead cranes. There is a 50-ton crane at the end of the wharf, and a 3-ton crane is mounted on a platform car.

The quality of incandescent light in London is inferior. The light is not steady, never above candle-power, but of a dull red color, and is often referred to by envious gas engineers as 4-watt red-hot hairpins. The expert, the bane of all electric companies in the United States, has a cousin in the engineer. They are of the same class as the experts, only they know less. The height of their ambition is to become "attached" to the staff of some noted engineer, and superintend or direct practical work without ever learning it by hard work and experience. Engine drivers earn 30 shillings a week; they are little more than oilers; fitters keep machines in repair; steam engineers overlook all this work; the engineers of the staff oversee the steam engineers, and the engineers in chief receive the salary and get the honors. Manual labor is deemed menial, and young men of the middle class shun it.

At the close of the paper a large number of views of the London stations were projected on the screen.

MEETING 404.

The Engineering Building.

BY PROFS. F. W. CHANDLER, G. LANZA, G. F. SWAIN, AND MR. 8. H. WOODBRIDGE.

The 404th and annual meeting of the SOCIETY OF ARTS was held in the Engineering Building of the Institute on Thursday, May 8th, at 8 P.M., President Walker in the chair.

After the reading of the records of the previous meeting the report of the Nominating Committee was presented, and officers were elected for the ensuing year.

The report of the Executive Committee was read and ordered placed upon the records. The President then announced the subject of the evening to be the New Engineering Building of the Institute, and introduced Prof. F. W. Chandler, who described the architectural features.

Prof. CHANDLER said: The Engineering Building of the Institute of Technology is built on Trinity Place, a short distance from the other buildings of the Institute. The structure measures 148 feet by 52 feet, and has six stories. Its height of 85 feet is the extreme limit allowed by the building laws when a wooden construction is used. Its position on the lot was very carefully considered in regard to future additions to the south on the property of the Institute; and, by mutual agreement with the abuttors, there will always be a clear area of 30 feet to the north.

The scheme of the building is what is known as modern mill construction. A row of cast iron columus, placed eight feet from center to center, runs lengthwise of the building, giving spans of twenty-four feet from column to wall. The strength of the brick wall is concentrated in buttresses opposite the columns, and thinner walls unite them, and because these thinner walls are not necessary for the stability of the building, the greater part of this space is occupied by windows, the heads of which extending between the beams, as there are no ceilings, to the underfloor gives that high light which is the most effective in lighting a large room. A pair of southern pine beams extends from each column to each side wall. These doubled beams

are in all cases bolted together with eight 4-inch iron bolts to each pair, leaving a space of one inch between for ventilation, kept open by iron washers. The beams are framed to fit snugly around the columns, and the ends of the abutting timbers are fastened together by dogs of 4-inch iron, the ends of which are turned down and driven into holes in the beams. These timbers are also fastened at the under side by lag screws through the caps of the columns. The other ends rest on cast-iron plates one inch thick, and are carried into the wall eight inches, and one inch of air space is left about the ends for ventilation. To tie these beams to the walls a one-inch bolt is put through each pair of beams eight inches from the wall, and at the same time through the eye of another one-inch bolt which lies between the timbers, the nut end being on the outside of the building, and pressing against a cast-iron washer. Across these paired beams are carried plank underfloors of spruce, four inches thick in the basement and three inches thick elsewhere. These planks are laid with splines. The upper floors throughout are of maple and inches thick. Between the lower and upper floors, in addition to the asbestos paper required by law, are three thicknesses of heavy deadening felt, and two of tarred paper.

The construction of the roof is like that of the floors.

It does not yet appear by whom the slow-burning construction, as applied to mills, has been evolved, or when was first made use of heavy timbers set wide apart carrying a solid floor. But for a long time after these floors were in use, even in Lowell, the roofs were bad either in form or structure until Mr. William B. Whiting, the Vice-President of the Boston Manufacturers Fire Insurance Co., sug. gested the adoption of what is called the deck roof, constructed like the floors, and the Engineering Building is a development of the Mutual Underwriters more than anyone else.

The structure throughout is of unusual strength, for the aim was to have a building which should be sufficiently free from vibration when the heavy machinery was running in the basement, to admit of experiments being made there, requiring delicate measurements, and because the four upper floors were to be chiefly used for draughting rooms. The iron columns decrease in size from the one in the basement measuring 11 inches in diameter with a 1-inch shell to the one in the sixth story, 6 inches in diameter with an inch shell. These